High efficiency radial piston pump or motor with improved flow pattern



United States Patent lnventor Appl. No. Filed Patented HIGH EFFICIENCY RADIAL PISTON PUMP OR MOTOR WITH IMPROVED FLOW PATTERN Primary Examiner-Mark Newman Assistant Examiner-Warren J. Krauss A ttorney Basseches and Basseches 2 Claims, 4 Drawing Figs.

US. Cl. 91/497,

91/498 ABSTRACT: A high efficiency radial piston pump or motor of 1m, (I F011) 1/06, the type disclosed in US. Pat. No. 3,345,9160f Oct. 10, 1967,

F l 3/96 and further characterized by an improved porting configura- Field of Search 103/161; tion which minimizes losses due to turbulence in transporting 230/177; 92/58; 91/497, 498 fluids to and from the cylinder bores.

l5 \H vl I 7 '1 iv, p\ j 1 I P 25 /2 27 V m i {I /7 f/ g I F I tion.

HIGH EFFICIENCY RADIAL PISTON PUMP OR MOTOR WITH IMPROVED FLOW PATTERN BACKGROUND OF THE INVENTION I. Field of the Invention This invention is in the field of radial piston pumps and motors of the general type shown in the above-noted US. Patent, which devices include a pintle shaft having circumferential inlet and outlet chambers, a cylinder block mounted for rotation about the pintle shaft and fluid ports leading from the cylinder bores to a bearing aperture fonned on the cylinder block for conducting fluids between thechambers and the bores.

2. Description of the Prior Art In my above referred to US. Patent, there is disclosed a radial piston pump or motor apparatus of high efficiency and reduced overall diameter as contrasted with similar types of apparatus theretofore known; The patented structure greatly increases efficiency by minimizing losses due to turbulence and by providing an apparatus in which the cross-sectional area of the passages leading to the bores equals or approximates the cross-sectional areas of the bores themselves,

without increasing theoverall diameter of the unit.

SUMMARY or THE INVENTION The invention may be summarized as directed to an im proved radial piston pump or motor having a further refined porting configuration as contrasted with the configuration disclosed in my US. Pat. No. 3,345,916.

As is the case in said patent, the axial dimension of the ports where they communicate with the pintle shah-discharge and charge areas is greater than the transverse dimension of said port at said position. The passages become progressively shorter in their longitudinal dimension and wider in their transverse dimension as they approach/and merge with the cylinder bores.

The passages of the present inventionare further characterized by being oriented or positioned within the block in such manner that no fluid flowing from the pintle to the cylinder will be required to flow lengthwise of the shaft to a point beyond the cylinder within the pintle shaft and thereafter flow in a direction having any component opposite the direction of flow of the fluid as it is travelling in the connected flow line in the pintle shaft.

By positioning the fluid ports in such manner that no retro movement of the fluid is experienced, an improved flow pattern between the pintle shaft and the cylinders is developed, which pattern results in even greater efficiencies than those experienced with the apparatus of U.S. Pat. No. 3,345,916.

Accordingly, it is an object of the invention to provide a radial piston pump or motor having improved ducts or ports for conducting the fluid from the pintle. shaft to the cylinder bores with minimumlosses. I

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, reference is made to the accompanying drawings, forming a part hereof, in which:

FIG. I is a vertical sectional view through a hydraulic pump or motor in accordance with the invention;

FIG. 2 is an offset section taken on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary horizontal section taken in the direction of the arrows 3-3 of FIG. 2;

FIG. 4 is a perspective representation of a porting configuration in accordance with a further embodiment of the inven- Referring now to the drawings, there is shown in FIGS. 1 and 2 largely diagrammatic representations of a radial piston pump or motor. In the drawings represents'a frame for supporting a reaction ring chassis 11 which may be shifted laterally to the right and left relative to the fixedly positioned pintle shaft 12 by operation of a control mechanism, exemplified in the illustrated embodiment as a screw control 13.

A rotatable reaction ring 14, separated from the ring 11 by bearings 15, engages against the outermostends of pistons 16,

which pistons are free to reciprocate within radially extending bores 17 formed in a cylinder block 18 rotatable about the pintle shaft 12. As is common in devices of this sort, the amount of reciprocal movement of the pump or motor is a function of the distance which the reaction ring axis is offset from the pintle shaft axis. A

A drive shaft 19 is connected with the block 18 for conjoint rotation therewith by any conventional means, such as the teeth 20, 21 lying within the slot 22 formed in the block.

The pintle shaft 12 is provided with pressure and discharge passages 23, 24 extending axially within the shaft and terminating in radially outwardly opening discharge chambers 25, 26. The chambers are separated by the usual bridge area 27.

It will be observed from the foregoing that fluid is charged and discharged to the appropriate chambers through the end 28 of the pintle shaft.

As best seen in FIGS. 1, 2 and 3, the cylinder bores 17 are communicated with the charge and discharge chambers 25, 26 by passages P which extend between the'bores l7 and the central bearing aperture 29 in the cylinder block.

It will be understood that the landsor bearing areas adjacent the ends of aperture 29 extend in sealing engagement with the pintle shaft 12 to both sides of the discharge areas 25, 26, to contain the fluid under pressure between the block and the pintle shaft.

As heretofore described, the apparatus isessentially identical to the noted patent, which is incorporated herein by reference.

The passages P of the present device are characterized in that no portion of the passages extend beyond the plane 30 normal to the pintle shaft and tangent to the edges of the bores 17 most remote from the end 28 of the pintle shaft. Similarly and preferably, the charge and discharge areas 25, 26 terminate on a line essentially coincident with said line.

As best seen from FIG. 3, the configuration of the passages P is such that the transverse dimension 31 of the passages at the inner circumference or bearing surface 29 is less than the diameters of the bores 17 and the axial extent 32 of such passages at the inner circumference is greater than the diameters.

The passages preferably flare outwardly in a transverse or widthwise dimension and progressively become shorter in the lengthwise dimension as they radially approach the bore. The

radial outermost ends of the passages merge smoothly with the bores. All portions of the passages Pare disposed within the block between the plane 30 and a second plane 33 defined, by the portion of the charge and discharge areas 25 26 nearest to the end 28 of the pintle shaft.

The advantages of the abovedescribed passage configuration and location may be best appreciated by comparing the same with the configuration depicted in my Patent No. 3,345,916. I

In the patented construction it will be seen that certain parts of the discharge areas of the pintle shaft and certain parts of the passages in the block extended beyond the plane 30 as defined in the instant application.- In such a construction, a fractional portion of the fluid transferred from the discharge areas to the cylinder bores flows inwardly, i.e. in a direction,

away from the end 28 of the pintle shaft, to a position beyond the cylinder bores and could enter into the .bores only by a flow pattern which included components directed back toward the end 28. A pattern including any such returning component will be herein referred to as a retro flow pattern."

I have determined that in an apparatus of this sort encompassing retro flow patterns, a degree of turbulence is created which offsets, to a minor extent, the efficiency gained through the provision of porting of the type shown in the patented construction. By limiting the porting so that it does not extend beyond the plane 30 andby comparably limiting the temiinal end of the discharge and charge chambers remote from the end 28 of the pintle shaft, such retro flow patterns are eliminated.

There is shown in FIG. 4 a further porting configuration which, while somewhat more difficult to fabricate, is considered to be slightly more efficient than even the configurations shown in the embodiments of FIGS. 1 to 3.

In the embodiment of FIG. 4, the arrow 34 indicates the direction of fluid flow in the pintle shaft. In this embodiment, the end of the flow passage furthest from the input and output end 28 of the pintle shaft is slightly angled in the direction of fluid flow within the pintle shaft, as indicated by the angle A '(rather than being perpendicular, as shown in FIGS. 1 to 3).

-As in the patented construction, the cross-sectional area of the passage at any point between the pintle shaft and the bore is preferably equal or substantially equal to the cross-sectional area of the bore itself although, of course, some of the advantages of the invention may be realized even where such constant area is not employed).

From the foregoing it will be seen that there is provided a radial piston pump or motor wherein increase of efficiency is obtained by the avoidance of retro flow patterns within the passages linking the cylinder bores with the discharge areas formed in the pintle shaft.

1 claim:

1. ln a hydraulic device of the radial piston type including a pintle shaft having axially extending, circumferential charge and discharge areas and axially directed input and output passages extending from one end of said shaft and communicating with said charge and discharge areas, respectively, a cylinder block having a bearing aperture rotatably mounted on said shaft and overlying said chargeand discharge areas, a plurality of angularly spaced apart, radially directed cylinder bores in said block, and a plurality of fluid transfer passages connecting said aperture with said bores, the axial dimension of said passages at said aperture exceeding the transverse dimension of said passages at said aperture and the diameter of said bores, said transverse dimension of said passages growing progressively larger and said axial dimension growing progressively smaller as said passages approach said bores, said device being characterized by substantially the entirety of said passages being positioned within an area in said block defined between a plane normal to said pintle shaft and tangent to the portions of said cylinder bores furthest from said one end of said pintle shaft and a plane normal to said shaft and extending through the portion of said charge and discharge areas nearest said one end.

2. A device in accordance with claim 1 wherein said portions of said discharge area do not extend beyond said plane tangent to said bores. 

